Do not assume that if a substance is not listed in IRIS it is not toxic.
A
great many toxic chemicals are not in the IRIS database including DIOXIN!

I ran into this dangerous situation when I was working with Teresa Mills
and the other folks in Columbus, Ohio in regard to their municipal
incinerator which was the greatest dioxin emitting incinerator in America.
The City Health Commissioner had been assuring the community that dioxin
was not toxic (this was in 1994!) This was accepted by the press, the
local government, and the community over the protestations of Teresa
and
her colleagues. When I asked the Commissioner (an MD I believe) why
he
thought dioxin wasn't toxic he explained that it was not in the EPA
IRIS
database which he depended on as his source of toxic substances. I
then
called the fellow who runs IRIS and he told me that there are many
toxic
substances not included in IRIS and that IRIS is a database which depends
on voluntary submissions. Their only function is to check the accuracy
of
the submissions.

I pointed out the danger of this by telling him of the Columbus experience
and he agreed that a warning of its incompleteness should be included
with
the database.

That was in 1994. I just checked the IRIS web page and dioxin is still
not
included and neither is the warning.